﻿A review of the spider genus Sinoalaria (Araneae, Theridiosomatidae), with the descriptions of four new species and two new combinations

﻿Abstract The spider genus Sinoalaria Zhao & Li, 2014 is redefined and reviewed. A total of ten species are studied, including four new species: S.chi Yu & Lin, sp. nov. (♂♀), S.shenhei Yu & Lin, sp. nov. (♀), S.shuidi Yu & Lin, sp. nov. (♀), S.xiaotu Yu & Lin, sp. nov. (♂♀). Two new combinations are proposed: Sinoalarianitida (Zhao & Li, 2012), comb. nov. and S.prolata (Zhao & Li, 2012), comb. nov., both transferred from Karstia Chen, 2010. The material of six known species were re-examined and photographed, including the type species, S.chengguanensis (Zhao & Li, 2012). A key is provided for all species of the genus, as well as diagnoses, illustrations, and a distribution map.


Introduction
is a replacement name for Alaria Zhao & Li, 2012, which was originally erected as a monotypic genus based on A. chengguanensis Zhao & Li, 2012 from China. It is a relatively small genus, distributed exclusively in South East Asia, with only four known species described so far (WSC 2023). All but the type species are from Laos and were described by Lin et al. (2014): S. bicornis (Lin, Li & Jäger, 2014), S. cavernicola (Lin, Li & Jäger, 2014) and S. navicularis (Lin, Li & Jäger, 2014). However, after 2014, no new species of this genus have been reported worldwide, and the diversity of this genus is still insufficiently known.
This paper reports our findings on the study of recently available samples from southwest China, Vietnam, Laos, and Thailand, which revealed four new species of Sinoalaria. Furthermore, two combinations are proposed based on morphological evidence and a preliminary molecular phylogeny (unpublished): S. nitida (Zhao & Li, 2012), comb. nov. and S. prolata (Zhao & Li, 2012), comb. nov., ex Karstia Chen, 2010. With that, the total number of Sinoalaria species reaches ten species. The goals of this paper are: 1) to conduct a comprehensive review of the genus Sinoalaria, provide an identification key and a distribution map for all species; 2) to describe the four new species under the name of S. chi Yu & Lin, sp. nov., S. shenhei Yu & Lin, sp. nov., S. shuidi Yu & Lin, sp. nov. and S. xiaotu Yu & Lin, sp. nov.; 3) to re-illustrate all six known species, including the type species and the two combinations.

Materials and methods
All specimens were preserved in 95% ethanol. Specimens were examined and measured with a Leica M205 C stereomicroscope. Further details were studied with an Olympus BX43 compound microscope. Male and female genitalia were examined and illustrated after dissection. Epigynes were removed and cleared in lactic acid before illustration. All vulvae were imaged after being embedded in Arabic gum. Photos were taken with a Canon EOS 60D wide zoom digital camera (8.5 megapixels) mounted on an Olympus BX43 stereomicroscope. The images were montaged using Helicon Focus 3.10 (Khmelik et al. 2006) image stacking software. All measurements in the paper are in millimeters. Leg measurements are given in the following sequence: total length (femur, patella, tibia, metatarsus, and tarsus).
The distribution map was generated with ArcGIS 10.5 (Environmental Systems Research Institute, Inc.). Locality coordinates for all species are copied from the original publications (see Zhao and Li 2012;Lin et al. 2014).
All examined materials are deposited in the Natural History Museum of Sichuan University in Chengdu (NHMSU), China, expect for the types of Sinoalaria chengguanensis and S. prolata in the Institute of Zoology, Chinese Academy of Sciences, Beijing, China (IZCAS).

Diagnosis.
Sinoalaria species can be recognised by the following combination of genitalic characters: In males, palpal tibia retrolaterally bears an apophysis (Figs 1B,D,3B,5B,D,7B,D,9B,D,15B,D) (vs retrolateral tibial apophysis is lacking in all other theridiosomatid genera); median apophysis distinct, stretching along the longitudinal axis of pedipalp with two curved, pointed distal ends (Figs 1A, 3A, C, 5A, D, 7A, C, 9A, C, 15A, C) (vs never seen in any other theridiosomatid genus); embolus long and whip-shaped, mostly enveloped in conductor (Figs 1A, C, 3A, C, 5A, C, D, 7A, C, 9A, C, 15A, C) (vs embolus not whip-shaped in almost all of theridiosomatid genera, embolus whip-shaped but proportionately much shorter and partly enveloped in Ogulnius O. Pickard-Cambridge, 1882, as in Coddington 1986. In females, the epigynal plate possesses a distinct scape (Figs 2E-G, 4E-G, 6D-F, 8E-G, 10E-G, 11C-E, G, 12D, E, 13D-F, 14C-E, 16E-G) (vs scape is absent, or present but reduced in some theridiosomatid genera); vulva centrally with a U-shaped medial structure (Figs 2G, 4G, 6F, 8G,  10G, 11E-G, 12E, F, 13F, 14E, 16G) (vs medial structure lacking, or present but V-shaped in some theridiosomatid genera); copulatory ducts rise and curl up to form two folds (or chambers, or bursae) at each side: the ventral one usually located anteriorly, with lower degree of sclerotization than the dorsal and posterior one (Figs 2G,4G,6F,8G,10G,12E,F,13F,14E,16G) (vs such conformation of the copulatory ducts is never seen in any other theridiosomatid genus). Description. See Zhao and Li (2012). Composition and distribution. Cymbium basally with a cluster of 6 setae; median apophysis extremely small, ≤ 1/3 of tegulum length, both proximal process and distal process are indistinct; the apex of conductor needle-shaped, sharp (Fig. 15)  Diagnosis. Males of S. bicornis resemble those of S. xiaotu sp. nov. in the general shape of the male palp. The palps of the two species share the similarly short median apophysis which is ≤ 1/2 of tegulum length, and the indistinct embolic base (     Diagnosis. Males of S. cavernicola and S. chi sp. nov. share the following features: the proximal process of median apophysis with a blunt and serrated tip, and the distal process of median apophysis with a slightly furcated apex (Figs 3A, 7A) (proximal process not serrated, distal process not furcated in all other Sinoalaria species, including S. chengguanensis and S. navicularis; Figs 5A, 9A), but can be differ from the latter by: (1) distal process of median apophysis long and narrow, slightly longer and distinctly narrower than base of median apophysis in S. cavernicola (short and wide, slightly shorter and narrower than base of median apophysis in S. chi sp. nov.) (cf. Fig. 3A and   long setae (Figs 1B,D,5B,D;15B,D) (such cluster of several long setae is absent in all other Sinoalaria species, as in Figs 3,7,9), but can be distinguished from the latter two by the distinctly visible embolic base, and by the large median apophysis which is longer than 1/2 of tegulum length in S. chengguanensis (embolic base indistinct, median apophysis relatively small, no more than 1/2 of tegulum length in S. bicornis and S. xiaotu sp. nov.) (cf. Fig. 5 and Figs 1, 15). The female of S. chengguanensis appears to be closely related to S. navicularis and S. shenhei sp. nov. in having a similarly shield-shaped, utterly exposed scape, and similar configurations of vulva (Figs 6D-F, 10D-F, 13D-F), but can be recognised from S. navicularis by the scape heavily sclerotized, with a small transverse opening at its distal end (vs almost completely membranous, rugose, distally with a curved, pocket-like hood) (cf. Fig. 6D-F and Fig. 10D-F); and from S. shenhei sp. nov. can be recognised by the tongue-shaped scape with a distinctly narrowed proximal part (vs scape shaped like an inverted bowling pin, slightly narrowed proximally) (cf. Fig. 6D-F and Fig. 13D-F), the dorsal and posterior folds of copulatory ducts nearly circular, slightly sclerotized (vs trapeziform, heavily sclerotized) (cf. Fig. 6F and Fig. 13F), and by the abdomen dorsally white with numerous small black spots (vs dorsum of abdomen basically black, with three bands which consisting of white small spots, forming a trident-shaped pattern) (cf. Fig. 6B, C and Fig. 13A).
Distribution. China (Guizhou) (Fig. 17). Etymology. The specific name is derived from the Chinese pinyin 'chǐ', which means 'tooth', referring to the tooth-shaped lower ramus on distal process of median apophysis; noun in apposition.

Sinoalaria chi
Diagnosis. Males of S. chi sp. nov. resemble those of S. cavernicola. The two species share a similarly slender and filiform embolus, sheet-shaped paracymbium with a spine-like tip, and the median apophysis with serrated proximal process and slightly bifurcated distal process but differ by: (1) distal process of median apophysis short and wide, slightly shorter and narrower than the base of median apophysis in S. chi sp. nov. (long and narrow, slightly longer and distinctly narrower than base in S. cavernicola) (cf. Fig. 7A and Fig. 3A); (2) the lower ramus on distal process of median apophysis tooth-shaped, apex sharp, distinctly longer than the indistinct upper ramus in S. chi sp. nov. (both rami distinct, are of equal length, the lower one with a relatively blunt tip in S. cavernicola) (cf. Fig. 7A    (4) embolic base relatively smaller, its width ca 1/2 of tegulum length in S. chi sp. nov. (embolic base wider than 2/3 of tegulum length in S. cavernicola) (cf. Fig. 7B and Fig. 3B). Females also resemble those of S. cavernicola in having a completely membranous, rugose scape which distally with a pocket-like hood (the combination of these features are absent in all other congeners), and the general shape of the endogyne but can be distinguished from the latter by the ventral and anterior folds of copulatory ducts represented by two oblong bursae, the dorsal and posterior folds represented by a longitudinal loop and a horizontal loop in S. chi sp. nov. (ventral and anterior folds represented by two more or less globular bursae, dorsal and posterior folds running horizontally, forming only one loop in S. cavernicola) (cf. Fig. 8G and Fig. 4G).
Description. Male (holotype) (Fig. 8A, B): Carapace shaped like a water drop, brown, darker in the front, without distinct pattern; pars cephalica distinctly narrowed, cervical groove and radial grooves faint. Anterior eye row distinctly recurved, posterior eye row slightly procurved. Sternum shield-shaped, dark. Mouthparts reddish brown. Legs uniformly yellowish, femora slightly darker. Abdomen round, dorsum basically black, with a lengthwise yellowish median stripe extending almost of whole abdomen length, gradually narrow posteriorly, with three pairs of yellowish speckles on either side; venter black centrally, yellowish marginally. Palp (Fig. 7A-D): Tibia small, cup-shaped, ca 1/3 length of cymbium. Retrolateral tibial apophysis small but distinct, thumb-like, ca 1/3-1/2 length of tibia. Cymbium narrow, ca 2.3× longer than wide, dorsally bears several long and sparse setae, basally without tufty setae. Paracymbium ca 1/8-1/7 length of cymbium, represented by a small sheet, distally bears a needle-shaped spine. Tegulum capacious, oval, 1.3× longer than wide; sperm duct distinct. Median apophysis large, located prolaterally to tegulum, consisting of a broad base and two process; proximal process ca 2/3 length of base, distally serrated; distal process wide, slightly shorter than base, distally slightly bifurcated, upper ramus indistinct, lower ramus tooth-shaped. Embolic base large, represented by enlarged tubercle, located at the 9-10 o'clock position to tegulum in retrolateral view, its width ca 1/2 tegulum length. The free part of embolus long and slender, filiform, in retrolateral view, arising at approximately the 8-9 o'clock position, forming a loop, terminating at ca 8 o'clock position, its tip curved behind embolic base. Conductor tubular and translucent, enveloping the second half of embolus, apex pointing retrolaterally.
Female ( Epigyne (Fig. 8C-E). Epigynal plate large, distinctly wider than long, the arrangement of the various parts of the vulva are faint through the tegument. Scape long, rugose, translucent, extending from posterior margin of epigynal plate, ca 1.8× plate length; apex blunt and slightly sclerotized, represented by a small pocket-like hood. Copulatory ducts strongly convoluted, located laterally to spermathecae: ventral and anterior folds of copulatory ducts represented by two oblong bursae, bursae surface membranous, ca 2/3 length of epigyne plate, the two bursae separated by ca 1.7× their widths; dorsal posterior folds tubular, heavily sclerotized and strongly convoluted, forming a longitudinal loop and a horizontal loop, finally connecting with ventral surface of spermathecae. Spermathecae bean-shaped, strongly sclerotized, ca 1/2 length of epigyne plate, 2× longer than wide, located centrally and juxtaposed, the two spermathecae closely spaced. Fertilization ducts short, ribbon-shaped, membranous, located on dorsal-basal surface of spermathecae; apical parts separated by ca 1.5× fertilization duct length, apex curved and sharp.
Distribution. Northern Vietnam (Fig. 17). ( Diagnosis. Males of S. navicularis can be distinguished from all other congeners by the navicular median apophysis (Fig. 9A). The female of S. navicularis is distinguished from other congeners except S. chengguanensis and S. shenhei sp. nov. by the scape with a moderate size, utterly exposed, like a shield attached to the abdomen (Figs 6D, 10E, 13D) (scape not as above, either distintly long and narrow, such as S. bicornis, S. cavernicola, S. chi sp. nov. and S. xiaotu sp. nov. as in Figs 2E-G, 4E-G, 8E-G, 16E-G, or distintly short and wide, such as S. nitida and S. shuidi sp. nov. as in Figs 11C-E, 14C-E), but differ from the latter two by the scape almost completely membranous, rugose (more sclerotized, not rugose in S. chengguanensis and S. shenhei sp. nov.) (cf. Fig. 10E-G and Figs 6D-F, 13D-F).
Distribution. China (Guangxi) (Fig. 17). ( Diagnosis. This species can be distinguished from all other species of the genus Sinoalaria by the wide, triangular, scape that protrudes vertically from the posterior epigynal margin (Fig. 12C-E).

Sinoalaria shenhei
Etymology. The specific name is an adjective and derived from the Chinese pinyin 'shēn hēi', which means 'pitch-black', referring to the basic color of body.
Diagnosis. The new species is similar to S. chengguanensis (Fig. 6) in the general appearance of the epigyne. From S. chengguanensis, the female of S. shenhei sp. nov. can be distinguished by the shape of the scape, the different shape and degrees of sclerotization of copulatory ducts, as well as the color of habitus: (1) scape shaped like an inverted bowling pin, slightly narrowed proximally in S. shenhei sp. nov. (scape tongue-shaped, proximal part distinctly narrowed in S. chengguanensis) (cf. Fig. 13D-F and Fig. 6D-F); (2) dorsal and posterior folds of copulatory ducts trapeziform, heavily sclerotized in S. shenhei  sp. nov. (nearly circular, slightly sclerotized in S. chengguanensis) (cf. Fig. 13F and Fig. 6F); (3) dorsum of abdomen basically black, with three bands which consisting of small white spots, forming a trident-shaped pattern in S. shenhei sp. nov. (abdomen dorsally white with numerous small black spots in S. chengguanensis) (cf. Fig. 13A and Fig. 6B, C).
Description. Female (holotype) (Fig. 13A, B): Carapace nearly pyriform, uniformly black; cervical groove and radial grooves faint. Anterior eye row recurved, posterior eye row almost straight in dorsal view. Sternum shield-shaped, centrally light orange with sparse setae, marginally dark. Mouthparts yellowish. Legs dark brown except black femur. Abdomen nearly round, posteriorly with a prominent caudo-dorsal hump, covered with sparse long setae, setal base sclerotized. Dorsum of abdomen basically black, with three bands consisting of small white spots forming a trident-shaped pattern. Venter of abdomen black, centrally with numerous brown small spots. Measurements: Total length 3.5. Epigyne ( Fig. 13C-F). Epigynal plate nearly as wide as long, spermathecae and copulatory ducts are faint through epigynal plate before dissection. Scape as long as epigynal plate, shaped like an inverted bowling pin, apex with a pocket-like hood; protruding from concaved posterior margin of epigynal plate. Copulatory ducts coils located anterolaterally to spermathecae: ventral and anterior folds represented by two hyaline and triangular bursae, ca 1/3 length of epigyne plate, the two folds widely separated by ca 2.1× their width; the dorsal and posterior fold trapezoid, heavily sclerotized, separated by ca 1.3× their diameters. Spermathecae fist-shaped, strongly sclerotized, located centrally and juxtaposed, not overlapping with copulatory ducts; the two spermathecae touch each other. Fertilization ducts short, acicular, membranous, located on posterior surface of spermathecae.
Male. Unknown. Distribution. Known only from the type locality (Fig. 17). Etymology. The specific name is derived from the Chinese pinyin 'shuǐ dī', which means water drop, referring to the scape that is shaped like a water drop; noun in apposition.

Sinoalaria shuidi
Diagnosis. This new species is similar to S. nitida in having the scape shorter than length of epigynal plate, with a swollen apex  (scapes of all other congeners, such as S. chengguanensis, S. chi sp. nov., S. shenhei sp. nov. and S. xiaotu sp. nov., which are no shorter than the length of epigynal plate, distally not swollen ;Figs 6E,F,8E,F,13E,F,16E,F), but can be distinguished by the scape shaped like a water drop, apex distinctly wider than its stem in S. shuidi sp. nov. (scape shaped like a nose, apex nearly as wide as stem in S. nitida), and by the spermathecae globular in S. shuidi sp. nov. (peanut-shaped in S. nitida) (cf. Fig. 14C-E and Fig. 11C-G).
Epigyne ( Fig. 14C-E). Epigynal plate nearly as wide as long, spermathecae and copulatory ducts are faint through epigynal plate before dissection. Scape relatively short, ca 3/4 of length of epigynal plate, with a slightly narrow stem and swollen apex, shaped like a water drop, apex with two pocket-like notches; proximal part originating from posterior portion of the plate. Copulatory ducts coils located laterally to spermathecae: ventral and anterior folds represented by two oval bursae, bursae surface hyaline, ca 1/2 length of epigyne plate, the two bursae separated by ca 2× their widths; dorsal and posterior folds heavily sclerotized, tubular, thick, not convoluted, extending horizontally to connect with ventral surface of spermathecae. Spermathecae nearly globular, strongly sclerotized, located centrally and juxtaposed, overlapping with distal part of dorsal and posterior folds of copulatory ducts; spermathecal diameter ca 2/5 length of epigyne plate, the two spermathecae closely spaced. Fertilization ducts short, acicular, membranous, located on posterior surface of spermathecae; apical parts separated by ca 2× fertilization duct, apex sharp.
Male. Unknown. Distribution. Known only from the type locality (Fig. 17). Etymology. The specific name is derived from the Chinese pinyin 'xiǎo tū', which means 'small apophysis', referring to the small median apophysis which is no more than 1/3 of tegulum length; noun in apposition.

Sinoalaria xiaotu
Diagnosis. Males of S. xiaotu sp. nov. can be distinguished from congeners except S. bicornis by the similar indistinct embolic base and the small median  1.3× length of the plate; proximally widest, then gradually narrowing distally, finally widening at apex, shaped like a dumbbell-shaped. Copulatory ducts coils located anterolaterally to spermathecae: ventral and anterior folds represented by two large bursae, bursae surface hyaline and egg-shaped; almost all part of dorsal and posterior folds covered by posterior part of spermathecae. Spermathecae nearly globular, strongly sclerotized, located centrally and juxtaposed, overlapping with dorsally postero-interior part of copulatory ducts; spermathecal diameter ca 1/3 length of epigyne plate, the two spermathecae closely spaced. Fertilization ducts short, acicular, membranous, located on posterior surface of spermathecae; apical parts separated by approximately the length of fertilization duct, apex sharp.
Distribution. Known only from Barbie National Park and Xuan Song National Park in Vietnam (Fig. 17).

Discussion
The genus Sinoalaria shows a distinct set of genital characters, such as palpal tibia retrolaterally bearing an apophysis in male, and copulatory ducts rising and curling up to form two folds (or chambers, or bursae) at each side in females. In contrast, the RTA is lacking and such conformation of the copulatory ducts has never been seen in any other theridiosomatid genus; therefore, Sinoalaria can be separated from all other genera of Theridiosomatidae. Furthermore, a preliminary molecular analysis of Theridiosomatidae from Southeast Asia was carried out, based on five targeted genes (two mitochondrial genes 16S and COI; three nuclear genes 18S, 28S, and H3). According to the unpublished results, the monophyly of Sinoalaria is strongly supported.
Sinoalaria nitida and S. prolata were assigned to the genus Karstia in the original publication (Zhao and Li 2012), although they show typical Sinoalaria features: copulatory ducts rise and curl up to form two folds (or chambers, or bursae) in both species . The females of Karstia species (known for K. upperyangtzica Chen, 2010 and K. cordata Dou & Lin, 2012 and several unpublished new species) share the following distinctive suite of characters, here contrasted with the corresponding condition in S. nitida and S. prolata: (1) scape large and semi-transparent, shaped nearly like an equilateral triangle, with an acute apex and two straight lateral margins, protruding posteriorly ( In view of the above-mentioned facts, it is currently impossible to discern any obvious derived features that could indicate a close relationship between the two species and the genus Karstia, leaving no doubts that our transfer is correct.

Funding
This study was supported by the National Natural Science Foundation of China to Yucheng Lin (NSFC-31972870, 31750002) and Hao Yu (NSFC-32060113, 31702006), the Natural Science Foundation of Guizhou Province to Hao Yu ([2020]1Y081).

Author contributions
Y.C.L. designed the study; Y.C.L. and C.C.F. performed the field work; J.S.Z. and C.C.F. conducted the lab work; Y.C.L. and C.C.F. analysed the data; J.S.Z., Y.C.L. and H.Y. interpreted the results and wrote the paper.